This circuit was found in Radio Electronics from the 90s. It converts capacitance into frequency in order to obtain a proportional voltage that can be measured in a common multimeter.
The circuit in the figure produces a perfectly rectangular waveform signal. For a 1 nF C1...
This circuit was found in a documentation for radio amateurs from the 70s. The integrated circuits...
We found this circuit at Modern Electronics in January 1991. The magazine no longer exists, but...